On a gentle north-east-facing slope at Bonabrocka, a complex arrangement of ancient earthworks lies completely invisible to anyone walking across it. No ridge, no hollow, no trace of disturbed ground gives the game away at surface level. The only way it has ever been seen is through aerial photography, where differences in crop growth betray the buried ditches beneath, producing what archaeologists call a cropmark.

What the aerial photograph reveals is a trivallate enclosure, meaning one defined by three concentric ditches, or fosses, rather than the single ditch more commonly associated with a ringfort. The innermost fosse has a diameter of roughly 25 metres, and two further fosses run closely together around it at a distance of approximately 15 metres outward, bringing the maximum external diameter to around 70 metres. Attached to the north-west is an annexe, an additional enclosed space that would have served some secondary function, perhaps for livestock or as a work area. Enclosures of this kind, with multiple concentric ditches, are relatively uncommon in the Irish archaeological record and tend to suggest either a site of some status or one that was remodelled and extended over time. Whether the Bonabrocka example was a high-status settlement, a ritual site, or something else entirely remains unknown without excavation.

A visitor to the field today would find nothing to see. The site rewards no particular season and requires no approach. It belongs, for now, entirely to the overhead view and to whatever lies undisturbed in the soil below.